Survey of perpetual motion machines

The possibility of perpetuum mobiles was first denied by science when the laws of thermodynamics were uncovered in the 19th century. Today, nobody in a research institute that receives grant funding would even try to work on such a machine. Nobody in academia would entertain the possibility of one existing in purely theoretical terms.

Despite all that, this has not stopped or slowed down amateurs from designing, building, and testing perpetuum mobiles. Some of the more fascinating designs use powerful magnets. Arguments against them usually point out that over a long span of time, the magnets will slowly become de-magnetized. While there may be little room for incredulity in 2019, those devices do actually keep turning for days at a time.